The Webra would do just fine. They are somewhat known as a powerhouse engine, at least in my experience. For that 4*60 it would be absolutely fantastic. 2-strokes are far from lower power, far from it. They have a different power-band, and some don't have quite the low-end punch of a 4-stroke. You can easily compare a 4-stroke .91 to your Webra, and the Webra should hold it's own very very well, and surpass in alot of ways.
On the other hand, the OS FP .40....that was just a basic sport engine, bushings all the way(no bearings). Although it would fly any trainer plane nicely, and would even fly a 4*40, the performance would not be even close to what a 4*60 would be with a Webra .61. A 4*60 with a Webra .61 would be a screamer for sure. Just get someone with experience to give you a hand though, unless your up to the task. Never-the-less, that would be the way I would go if I had a .61 sitting there already.
This combo gets my vote.